Bottom Line:
The knockdown of LvLRRFIP2 by RNA interference resulted in higher cumulative mortality of L. vannamei upon V. parahaemolyticus but not S. aureus and WSSV infections.The expression of L. vannamei AMP genes were reduced by dsLvLRRFIP2 interference.These results indicate that LvLRRFIP2 has an important function in antibacterials via the regulation of AMP gene expression.

pone-0057456-g008: The expression of L. vannamei AMPs after dsLvLRRFIP2 was knocked down.The relative expression of the L. vannamei AMP genes ((A) LvPEN2, (B) LvPEN4, (C) LvCrustin, (D) LvALF1, (E) LvLyz1, (F) LvLyz2) were compared against the PBS and dsEGFP injection group at the corresponding times. Relative expression values were normalized to LvEF1α. The results are based on three independent experiments and expressed as mean values±SD. Statistical significance was calculated by the Student’s t-test (*indicates p<0.05 and **indicates p<0.01 compared with EGFP dsRNA injection group.

Mentions:
Considering that the knockdown of LvLRRFIP2 led to significantly increased mortality after V. parahaemolyticus infection (Fig. 7B), the expressions of six AMP genes were observed in LvLRRFIP2 knockdown L. vannamei. Fig. 8 shows that LvPEN4 underwent a brief period of downregulation at 0.5 d, 1 d, and 2 d after dsLvLRRFIP2 injection. However, the expression level of LvPEN4 was not significantly different in the dsLvLRRFIP2 and dsEGFP injection groups (Fig. 8B). Compared with the dsEGFP injection group, the expression level of LvPEN2, LvCrustin, LvALF1, LvLyz1, and LvLyz2 decreased at all detected times in the dsLvLRRFIP2 injection group (Figs. 8A, 8C, 8D, 8E, and 8F, respectively). All the results corresponded to the increase of the cumulative mortality of L. vannamei in the LvLRRFIP2 dsRNA group challenged with V. parahaemolyticus.

pone-0057456-g008: The expression of L. vannamei AMPs after dsLvLRRFIP2 was knocked down.The relative expression of the L. vannamei AMP genes ((A) LvPEN2, (B) LvPEN4, (C) LvCrustin, (D) LvALF1, (E) LvLyz1, (F) LvLyz2) were compared against the PBS and dsEGFP injection group at the corresponding times. Relative expression values were normalized to LvEF1α. The results are based on three independent experiments and expressed as mean values±SD. Statistical significance was calculated by the Student’s t-test (*indicates p<0.05 and **indicates p<0.01 compared with EGFP dsRNA injection group.

Mentions:
Considering that the knockdown of LvLRRFIP2 led to significantly increased mortality after V. parahaemolyticus infection (Fig. 7B), the expressions of six AMP genes were observed in LvLRRFIP2 knockdown L. vannamei. Fig. 8 shows that LvPEN4 underwent a brief period of downregulation at 0.5 d, 1 d, and 2 d after dsLvLRRFIP2 injection. However, the expression level of LvPEN4 was not significantly different in the dsLvLRRFIP2 and dsEGFP injection groups (Fig. 8B). Compared with the dsEGFP injection group, the expression level of LvPEN2, LvCrustin, LvALF1, LvLyz1, and LvLyz2 decreased at all detected times in the dsLvLRRFIP2 injection group (Figs. 8A, 8C, 8D, 8E, and 8F, respectively). All the results corresponded to the increase of the cumulative mortality of L. vannamei in the LvLRRFIP2 dsRNA group challenged with V. parahaemolyticus.

Bottom Line:
The knockdown of LvLRRFIP2 by RNA interference resulted in higher cumulative mortality of L. vannamei upon V. parahaemolyticus but not S. aureus and WSSV infections.The expression of L. vannamei AMP genes were reduced by dsLvLRRFIP2 interference.These results indicate that LvLRRFIP2 has an important function in antibacterials via the regulation of AMP gene expression.